The present invention relates to a cylinder apparatus in a sheet-fed offset rotary printing press with a turn-over mechanism, for adjusting, with respect to the grippers of a double-diameter cylinder, the phase of a phase-changeable suction member which draws by suction and holds the trailing edge of a sheet gripped and conveyed by the grippers and for fixing the suction member to a cylinder body.
As shown in U.S. Pat. No. 4,831,929, a conventional cylinder apparatus for a printing press has a cylinder body having an axial hole extending through the central portion in the axial direction, a pair of left and right side plates which are in contact with the two end faces of the cylinder body and support suction heads, press rods which urge the side plates against the two end faces of the cylinder body and fix the side plates to the cylinder body, and a fixing shaft which is inserted in the axial hole of the cylinder body and moved to fix and release the side plates to and from the cylinder body with the press rods.
According to the structure of the conventional cylinder apparatus, when the fixing shaft is to be moved in the axial direction in the axial hole of the cylinder body in order to adjust the phase of a suction head with respect to the gripper, a screw member threadably engaging with the fixing shaft is pivoted manually. This operation not only poses a burden to the operator but also cannot be automatized.